New jeep. Mpg / gearing questions

[Stan H]

I was just wondering about the people on here saying they went with lower gears and it increased their mileage and reduced the shifting back and forth 7th to 8th to 7th. I suppose that would be reduced by keeping you in 7th...

Tire/wheel weight is a large factor in mileage and brake performance. The more rotating mass you have, the more work it takes to get moving or to stop.


Same here! Speed is the enemy of MPG on these things. Meanwhile my Challenger gets it's best mileage between 85 and 90mph.

But its a sleek aerodynamic car vs. A Retangular box on wheels 🛞

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[Chasm]

But its a sleek aerodynamic car vs. A Retangular box on wheels 🛞

Well, a Challenger isn't exactly aerodynamic, but when compared to a Jeep...

 

[mtudb24]

Yes sir. The old one was calibrated by dealership when they did the lift & tires.
this new one has a tazer connected. & it’s set up.

I was told by the dealer they could only calibrate to 35's which is what my dealer did when I went with the 35's when my jeep was brand new (dealer installed Mopar 2" lift and put my 35's on that I brought them). When I went to 37's back at the end ob May, they said no can do as even the JL Recon's only had 35's.

Had to buy a Tazer to calibrate the 37's.

In the 3200 miles I have driven with the 37's on a 3.6L and 4:10's, I'm averaging 16.7mpg.
Very little highway driving.

 

[djthumper]

I think the largest impact on your MPG is that roof rack. Keep the rack on the bed, remove the roof rack. I have a half rack for my roof, I lose about 3 MPG when that is up there.

 

[WILDHOBO]

I was told by the dealer they could only calibrate to 35's which is what my dealer did when I went with the 35's when my jeep was brand new (dealer installed Mopar 2" lift and put my 35's on that I brought them). When I went to 37's back at the end ob May, they said no can do as even the JL Recon's only had 35's.

Had to buy a Tazer to calibrate the 37's.

In the 3200 miles I have driven with the 37's on a 3.6L and 4:10's, I'm averaging 16.7mpg.
Very little highway driving.

They’re lying. But that’s what dealers do, so I guess it’s in the training.

 

[WILDHOBO]

I was told by the dealer they could only calibrate to 35's which is what my dealer did when I went with the 35's when my jeep was brand new (dealer installed Mopar 2" lift and put my 35's on that I brought them). When I went to 37's back at the end ob May, they said no can do as even the JL Recon's only had 35's.

Had to buy a Tazer to calibrate the 37's.

In the 3200 miles I have driven with the 37's on a 3.6L and 4:10's, I'm averaging 16.7mpg.
Very little highway driving.

Switch from the Midwest to mountains and that will drop to 13.

 

[Kinz384]

I think the largest impact on your MPG is that roof rack. Keep the rack on the bed, remove the roof rack. I have a half rack for my roof, I lose about 3 MPG when that is up there.

I’ll try it

 

[Stan H]

I was told by the dealer they could only calibrate to 35's which is what my dealer did when I went with the 35's when my jeep was brand new (dealer installed Mopar 2" lift and put my 35's on that I brought them). When I went to 37's back at the end ob May, they said no can do as even the JL Recon's only had 35's.

Had to buy a Tazer to calibrate the 37's.

In the 3200 miles I have driven with the 37's on a 3.6L and 4:10's, I'm averaging 16.7mpg.
Very little highway driving.

Alot of times even with Tazer or flashcal the "37" denomination is not what you truly need put in the computer.
On mine for instance runny Mickey 35" MT's and when the flashcal plus did the auto calibrate it set it at 33.25 . Runs out really well and I average 18+ all the time. When setting them and you may well know this already measure the tire on the blacktop compressed with the jeeps weight and insert that as the tire size alot of times it will be less that what ypu think it is.

 

[Kinz384]

Alot of times even with Tazer or flashcal the "37" denomination is not what you truly need put in the computer.
On mine for instance runny Mickey 35" MT's and when the flashcal plus did the auto calibrate it set it at 33.25 . Runs out really well and I average 18+ all the time. When setting them and you may well know this already measure the tire on the blacktop compressed with the jeeps weight and insert that as the tire size alot of times it will be less that what ypu think it is.

Yes sir. I’ll redo in new 37’s. Previous owner had set. Something like 36.7

 

[mtudb24]

Switch from the Midwest to mountains and that will drop to 13.

No doubt about that. Thankfully I don't

 

[mtudb24]

Alot of times even with Tazer or flashcal the "37" denomination is not what you truly need put in the computer.
On mine for instance runny Mickey 35" MT's and when the flashcal plus did the auto calibrate it set it at 33.25 . Runs out really well and I average 18+ all the time. When setting them and you may well know this already measure the tire on the blacktop compressed with the jeeps weight and insert that as the tire size alot of times it will be less that what ypu think it is.

Yup. BFG's are so small compared to what they classify them as. I think mine is set 36..2 or 36.3

 

[professorkx]

In my 2014 JK Rubicon with the 3.6, I routinely got 16.9 mpg. For a trip on the Rubicon Trail, I installed a roof rack, and boom…13 mpg. I rarely drive much over 60mph, and did the same on the trip to/from the Rubicon.
when I returned home, removed the roof rack and I was back to 16.9 mpg.

As a test, remove everything causing drag and the slowly add it back, checking your mpg as you add things back.

 

[WILDHOBO]

Yup. BFG's are so small compared to what they classify them as. I think mine is set 36..2 or 36.3

They are, but they all act differently depending on pressure. I have my mickeys set at 36.0 and my Speedo is perfect. And they’re way larger than bfgs.

 

[Stan H]

They are, but they all act differently depending on pressure. I have my mickeys set at 36.0 and my Speedo is perfect. And they’re way larger than bfgs.

Thats more akin to what the flashcak set my 35's at choosing 33.25 and my speedometer is dead on also . I even GPS 'ed it .

 

[CVrubi]

Well if anything else I’m glad you submitted this post because I’m riding on 35 Nitto Ridge Grapplers on my 2022 Rubicon and have been itching for 37s. Love the look of your truck. Now I’m thinking of keeping the 35s. I average @15-16mph here in flat Florida.

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